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Biomedical subjects

L Czer

Publications and source records attributed to L Czer.

13 recordsLinked to original sources
PubMed1995

Confirmation of the safety of autologous blood donation by patients awaiting heart or lung transplantation. A controlled study using hemodynamic monitoring.

BACKGROUND: Though earlier investigations have demonstrated the efficacy of autologous blood transfusion in reducing allogeneic blood exposure in patients undergoing heart or lung transplantation, questions remain regarding the safety of blood donation by patients with severe heart or lung disease. METHODS: Response to autologous blood donation by candidates for heart and lung transplantation and a group of age- and gender-matched control subjects was studied. Heart rate, blood pressure, oxygen saturation, and cardiac rhythm were examined before and after phlebotomy, and response to orthostatic challenge was evaluated. Patients were also questioned regarding impressions of changes in subjective sense of well being. Differences between patients and control subjects were evaluated by the paired t test and Fisher's exact test. An alpha of 0.05 was used in all testing to determine statistical significance. RESULTS: Eighteen candidates for heart transplantation, 16 candidates for lung transplantation, and their matched control subjects were studied. Though patients and control subjects differed with respect to baseline hemodynamic measurements, significant differences between the groups' responses to phlebotomy were not observed. After whole blood donation, orthostatic challenge resulted in a mean change in mean arterial pressure of -2.1 mm Hg in candidates for heart transplantation compared with a mean of +3.6 mm Hg in their control subjects (p = 0.062). In candidates for lung transplantation there was a mean change of +2.2 mm Hg after orthostatic challenge versus a mean change of +8.5 mm Hg in their control subjects (p = 0.052). Furthermore, no changes in cardiac rhythm or arterial oxygen saturation were detected. CONCLUSIONS: The hemodynamic effects of autologous blood donation in a group of patients with significant cardiac or pulmonary disease were not different from those observed in patients considered acceptable candidates for autologous blood collection. On the basis of these objective findings, we believe that patients with less severe degrees of heart or lung disease should not be excluded from participation in autologous blood donation programs.

Blood Transfusion, Autologous↗
PubMed1994

Intravenous immunoglobulin suppression of HLA alloantibody in highly sensitized transplant candidates and transplantation with a histoincompatible organ.

Patients awaiting solid organ transplantation who are highly sensitized to HLA antigens remain problematic in terms of finding compatible (crossmatch-negative) donors. We have used intravenous gammaglobulin (IVIG; 10% Gamimune N) to determine both its efficacy in reducing panel-reactive antibodies in vitro and the prognostic value of the in vitro testing for in vivo efficacy. In 18 patients with PRAs ranging from 40 to 100% (mean: 77%) we found a reduction in absolute PRA of 4-70% (mean decrease: 35%; percent inhibition: 4-100%; residual PRA 0-96%). In 7 cases, the residual antibody specificity could be easily determined and often appeared to include a short HLA-A2. This was independent of A2 subtype as determined by PCR-SSOP. Testing the IVIG on a panel of 21 HLA reagent alloantisera resulted in heterogeneous inhibitory patterns (7 complete, 3 partial, 8 differential, 3 none) independent of titer or specificity. In vivo administration to a 13-year-old kidney patient awaiting retransplant resulted in a PRA drop from 95% to 15% and successful retransplantation (now 11 months post-transplant). More impressively, successive in vivo administration of IVIG to a sensitized (anti-HLA-A2, A68, A69; B57, B58) heart transplant candidate resulted in successful transplantation with an A2+ histoincompatible heart. The patient experienced only one subclinical humoral rejection in the first 5 months posttransplant. Biochemical studies to determine the effective component of IVIG show that it is the IgG fraction and not soluble antigen or the minor IgM or IgA contaminants that is responsible. This suggests an antiidiotypic modulation of anti-HLA antibodies in vitro and in vivo.

HLA Antigens↗
PubMed1993

Safety and efficacy of preoperative donation of blood for autologous use by patients with end-stage heart or lung disease who are awaiting organ transplantation.

Many patients are, perhaps inappropriately, denied the benefits of autologous blood transfusion, because they are thought to be too ill to donate blood safely. The safety and efficacy of autologous blood donation by selected patients with end-stage heart or lung disease who are awaiting organ transplantation were studied to determine if even these critically ill patients could be suitable candidates for autologous blood donation. Seventy-two adults awaiting heart or lung transplantation were evaluated for autologous blood donation in a hospital-based blood collection facility. Phlebotomy was performed if the patient met the required medical eligibility protocol, and if he or she consented to participate. Units of blood were separated into packed red cells and plasma and stored in a frozen state. Of 48 heart transplant candidates, 31 (65%) were each able to donate 1 to 8 units of blood. The median number of exposures to allogeneic components was 1 for patients who donated and 7 for nondonors (p = 0.0141). Among patients who donated, 54 percent required allogeneic components, as compared to 88 percent of nondonors (p = 0.0968). Of 24 lung transplant candidates, 15 (63%) made 1 to 6 donations each. The median number of exposures to allogeneic components was 0 for donors and 2 for nondonors (p = 0.1871), but only 45 percent of donors required allogeneic components, as compared to 100 percent of nondonors (p = 0.0418). No serious complications during or following phlebotomy were observed. It is concluded that autologous blood donation by patients with end-stage heart or lung disease may be safe.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Effect of prosthetic aortic valve design on the Doppler-catheter gradient correlation: an in vitro study of normal St. Jude, Medtronic-Hall, Starr-Edwards and Hancock valves.

To evaluate the normal range of Doppler-derived velocities and gradients, their relation to direct flow measurements and the importance of prosthetic valve design on the relation between Doppler and catheter-derived gradients, five sizes of normal St. Jude bileaflet, Medtronic-Hall tilting disc, Starr-Edwards caged ball and Hancock bioprosthetic aortic valves were studied with use of a pulsatile flow model. A strong linear correlation between peak velocity and peak flow, and mean velocity and mean flow, was found in all four valve types (r = 0.96 to 0.99). In small St. Jude and Hancock valves, Doppler velocities and corresponding gradients increased dramatically with increasing flow, resulting in velocities and gradients as high as 4.7 m/s and 89 mm Hg, respectively. The ratio of velocity across the valve to velocity in front of the valve (velocity ratio) was independent of flow in all St. Jude, Medtronic-Hall, Starr-Edwards and Hancock valves when the two lowest flow rates were excluded for Hancock valves. Although Doppler peak and mean gradients correlated well with catheter peak and mean gradients in all four valve types, the actual agreement between the two techniques was acceptable only in Hancock and Medtronic-Hall valves. For St. Jude and Starr-Edwards valves, Doppler gradients significantly and consistently exceeded catheter gradients with differences as great as 44 mm Hg. Thus, Doppler velocities and gradients across normal prosthetic heart valves are highly flow dependent. However, the velocity ratio is independent of flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic Valve↗
PubMed1992

Color Doppler regurgitant characteristics of normal mechanical mitral valve prostheses in vitro.

BACKGROUND: To evaluate normal regurgitant characteristics of St. Jude (SJ) and Medtronic-Hall (MH) mitral valves, four sizes (25-31 mm) of each were studied in a pulsatile flow model. METHODS AND RESULTS: Regurgitant flow was measured by flowmeter at left ventricular pressures of 80, 130, and 180 mm Hg. Peak regurgitant flow rates ranged from 6.2 to 12.7 cm3/sec in SJ valves and from 7.9 to 17.5 cm3/sec in MH valves. Regurgitant orifice areas calculated from the Doppler continuity equation ranged from 1.6 to 2.0 mm2 in SJ valves and from 2.2 to 2.9 mm2 in MH valves. Regurgitant volumes across the closed valve at a left ventricular pressure of 130 mm Hg were normalized to an ejection time of 280 msec and ranged from 1.5 to 1.9 cm3 in SJ valves and from 2.1 to 2.8 cm3 in MH valves. Jets were imaged by color Doppler in six rotational planes, and jet size and morphology were compared with those of regurgitant jets from circular orifices with sizes comparable to the calculated prosthetic valve regurgitant orifices (1.1-3.1 mm2). SJ valves showed two converging jets from the pivot points, one central jet, and a variable number of peripheral jets. The mean color jet area derived from the six image planes ranged from 1.6 to 5.3 cm2. Aliasing occurred only close to the valve (maximal distance 0.5-2.0 cm). MH valves showed a large central jet with a maximal length of aliased flow between 2.0 and 5.5 cm. Depending on valve size, driving pressure, and image plane, one or two small peripheral jets were found. These jets did not show aliasing in any case. The mean color jet area ranged from 5.1 to 11.0 cm2. Jets originating from circular orifices of comparable size showed jet areas from 5.5 to 13.9 cm2 and aliasing distances from 3.3 to 7.3 cm. At similar regurgitant orifice areas, driving pressures, and regurgitant flows, the measured color areas and aliasing distances were smallest in SJ valves, larger in MH valves, and largest in simple circular orifices. CONCLUSIONS: Large, complex regurgitant jets can be found in normal closed SJ and MH valves by color Doppler, although regurgitant flow volume is minimal. Jet size and velocity distribution differs markedly between SJ valves, MH valves, and circular orifices, even with comparable driving pressure, regurgitant orifice area, and regurgitant volume. The characteristic patterns of normal regurgitation must be recognized to avoid incorrect diagnoses of pathological regurgitation in SJ and MH prosthetic valves. MH valves should not be removed solely on the basis of a central regurgitant jet with a long aliasing distance. Peripheral jets in MH valves and all jets in SJ valves should be considered normal as long as no or only minimal aliasing is present. In contrast, peripheral jets with significant aliasing may represent strong evidence of pathological regurgitation.

Blood Flow Velocity↗
PubMed1990

Discrepancies between Doppler and catheter gradients in aortic prosthetic valves in vitro. A manifestation of localized gradients and pressure recovery.

To evaluate possible causes of discrepancy between Doppler and catheter gradients across prosthetic valves, five sizes (19-27 mm) of St. Jude and Hancock valves were studied in an aortic pulsatile flow model. Catheter gradients at multiple sites distal to the valve were compared with simultaneously obtained Doppler gradients. In the St. Jude valve, significant differences between Doppler and catheter gradients measured 30 mm downstream from the valve were found: Doppler gradients exceeded peak catheter gradients of 10 mm Hg or more by 81 +/- 35% (15 +/- 3.6 mm Hg), and mean catheter gradients by 71 +/- 11% (10.3 +/- 2.5 mm Hg). When the catheter was pulled back through the tunnel-like central orifice of the valve, high localized gradients at the valve plane and significant early pressure recovery were found. When the catheter was pulled back through the large side orifices, gradients at the same level were only 46 +/- 6% of the central orifice gradients (mean difference, 7.6 +/- 4.5 mm Hg). Doppler peak and mean gradients showed excellent agreement with the highest central orifice catheter gradients (mean difference, 1.0 +/- 3.1 and 0.9 +/- 1.5 mm Hg, respectively). A significantly better agreement between Doppler and catheter gradients at 30 mm was found for the Hancock valve, although Doppler peak and mean gradients were still slightly greater than catheter gradients. Doppler gradients exceeded catheter gradients by 18 +/- 10% (3.4 +/- 1.9 mm Hg) and 13 +/- 11% (2.1 +/- 0.9 mm Hg), respectively. When the catheter was pulled back through the valve, the highest gradients were found approximately 20 mm distal to the valve ring.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Transient hemodynamic dysfunction after myocardial revascularization. Temperature dependence.

We studied hemodynamics and the effects of right atrial pacing (110 beats/min) following complete myocardial revascularization and hypothermic multidose potassium crystalloid cardioplegia in 12 patients with a normal preoperative left ventricular ejection fraction (LVEF). Measurements were made immediately preoperatively, postoperatively at specified temperatures during the rewarming period (90 degrees F, 94 degrees F, and 98 degrees F), and at 24 hours. No patient had a perioperative myocardial infarction. At 90 degrees F, hemodynamics were characterized by significant decreases in cardiac index, stroke volume index, and left ventricular stroke work index (LVSW) and an increase in systemic vascular resistance index (SVRI) compared to preoperative values (p less than 0.05). Right atrial pacing significantly increased cardiac index preoperatively and 24 hours postoperatively, but not during the rewarming period. Over the entire rewarming period (90 degrees F to 98 degrees F), each of the following variables correlated with temperature: cardiac index (r = 0.71 in sinus rhythm and r = 0.66 with right atrial pacing); stroke volume index (r = 0.33 and 0.66); SVRI (r = -0.80 and -0.64); LVSW (r = 0.37 and 0.73); and heart rate in sinus rhythm (r = 0.51). During the rewarming period, there was an inverse relationship between cardiac index and SVRI (r = -0.87). In conclusion, after myocardial revascularization: (1) transient hemodynamic dysfunction occurs during the rewarming period (90 degrees F to 98 degrees F); (2) this dysfunction is temperature-dependent; and (3) right atrial pacing at 110 beats/min does not improve hemodynamic function during the rewarming period. Temperature must be considered in the evaluation of left ventricular and hemodynamic function following myocardial revascularization.

Adult↗
PubMed1979

Cardiorespiratory monitoring in postoperative patients: I. Prediction of outcome and severity of illness.

An index for prediction of outcome for use as a measure of the severity of illness was developed by a nonparametric multivariate analysis of cardiorespiratory data from 113 critically ill postoperative general surgical patients. This severity (predictive) index was based on a computerized algorithm that compares a given observed value with the frequency distributions of survivors and nonsurvivors. The difference in the mean values of this index for survivors and nonsurvivors was statistically significant (p less than 0.001) during each stage of shock. Sensitivity of the index in prediction of survival ranged from 70-93% depending upon stage, the specificity of the index ranged from 76-92%, and the predictive accuracy ranged from 87-96%. The severity index is used as a process measure to track the course of critically ill patients and to evaluate the efficacy of alternative therapies.

Cardiovascular System↗
PubMed1979

Cardiorespiratory monitoring in postoperative patients: II. Quantitative therapeutic indices as guides to therapy.

Immediate (proximate) and late (optimal) therapeutic goals for critically ill postoperative general surgical patients were based on the frequency distributions of cardiorespiratory data of the survivors immediately after resuscitation and in the late stage of shock, respectively. An algorithm was developed which expresses in quantitative terms the distance from observed values for each variable to both of these therapeutic goals. Further, composite indices were also made of related cardiorespiratory variables that reflect the important aspects of acute circulatory failure and its therapy; i.e., volume, flow, tissue perfusion, oxygen transport, and bodily response to stress. The therapeutic indices of nonsurvivors were found to have greater mean deficits that survivors (p less than 0.05) during all but the middle stage of shock. The therapeutic indices greatly aid in the organization and display of monitored cardiorespiratory variables by expressing the circulatory defects in easily understood indices that can be related to therapeutic interventions. Moreover, the interactions of the various aspects of cardiorespiratory function before and after therapy may be easily observed.

Cardiovascular System↗
PubMedDate not supplied

Serum cytokine levels in heart allograft recipients: correlation with findings on endomyocardial biopsy.

The ability to detect rejection of human cardiac allografts depends on endomyocardial biopsy diagnosis. Because cytokines are known to mediate allograft rejection events, we chose to examine serum levels of specific cytokines and receptors (interleukin-2 [IL-2], IL-2 receptor [IL-2R], and tumor necrosis factor alpha [TNF-alpha]) and to correlate those levels with findings on endomyocardial biopsy. Sequential sera samples from 23 cardiac allograft recipients were examined for the cytokine levels mentioned, and data correlated with findings on endomyocardial biopsy. Briefly, no statistically correlation of serum cytokine or receptor levels with the stage of allograft rejection was found. When sequential serum cytokine levels were determined in patients experiencing humoral and cellular allograft rejection events, the levels of TNF-alpha appeared to correlate well with endomyocardial biopsy findings. IL-2 and IL-2R levels in two patients who never experienced rejection were elevated on occasion, but TNF-alpha levels were always negative. In summary, measurement of serum cytokine (IL-2, IL-2R) levels in cardiac allograft recipients does not appear to correlate with findings on endomyocardial biopsy; however, elevated levels of TNF-alpha appear to predict more severe humoral allograft rejection episodes and may be helpful in this regard.

Adolescent↗